Whenever cataracts or other conditions require, the natural lens of the human eye can be removed and replaced with an intraocular lens. An intraocular lens comprises an optic or lens and one or more fixation members for fixing the lens in the proper position within the eye so that the optic can direct light toward the retina.
In one common form of intraocular lens, the optic is constructed of a hard, non-deformable material, such as polymethylmethacrylate (PMMA). In a second type of intraocular lens, the optic is constructed of a deformable material, such as silicone or hydrogel. A deformable optic can be rolled or folded for insertion through an incision into the eye. An important advantage of an intraocular lens having a deformable optic is that, when it is rolled or folded, it can be inserted through a relatively small incision into the eye. This reduces the trauma to the patient and provides other advantages.
One problem with an intraocular lens having a deformable optic is in supporting it in an acceptable manner within the eye. One prior art approach is to employ fixation members which are integral with the optic. However, because of the soft, deformable nature of the optic material, it is necessary to make the integral fixation members relatively thick in order that they will have sufficient thickness to adequately retain and position the optic within the eye. Without this necessary thickness, the fixation members may buckle under the generally radial compressive load imposed by the posterior capsule as the posterior capsule shrinks following removal of the natural lens. This causes the optic to tip unacceptably, causing the image being transmitted through the optic to be deflected away from the retina, resulting in blurred and unreliable vision. The problem is that thickening of the integral fixation members gives the rolled or folded intraocular lens a larger cross-sectional area than would exist without such thickening, and this, in turn, requires a larger incision.
Another approach is to utilize separate fixation members and attach them to the optic. These separate fixation members, which are commonly constructed of PMMA or polypropylene, are typically fine hair-like strands. It is somewhat difficult to attach these fine hair-like strands to a deformable optic in a way that will assure that the strands will not pull out from the deformable optic.
What is needed is a support system for a deformable intraocular lens wherein a fixation member is easily attached to the optic and has the characteristics necessary to ensure that the optic does not tend to tilt undesirably in the manner described above.